Seam structure for fourdrinier type screen fabric and method of making same



N 1963 J. M. DE BELL ETAL 3,109,219

SEAM STRUCTURE FOR FOURDRINIER TYPE SCREEN FABRIC AND METHOD OF MAKINGSAME Filed June 21, 1961 I a Q a AKA INVENTORS JOHN M- DGBELL WESLEYLARSON and K5 VIN W- FL YNN av fwd- 72nd fiwfmmsys United States Patent3,109,219 SEAM STRUCTURE FGR FGURDIER TYPE SCREEN FABRIC AND METHOD OFMAKING ARE John M. De Bell, Longrneadow, Mass, and Wesley Larson andKevin W. Flynn, Hazardville, Conm, assignors, by mesne assignments, toCheney Bigelow Wire Works, Inc, Sprinfield, Mass, a corporation ofDeltaware Filed June 21, 1961, Ser. No. 11$,7ll2 22 Claims. (Cl. 2374)This invention relates to seam or joint structures, and method of makingthem, in fourdrinier type screen fabrics, in which the warp elements, atleast, are formed of synthetic organic yarns or filaments, or of yarnsor filaments containing synthetic organic material such as glass yarnsor filaments coated with a synthetic organic material.

Fourdrinier type screen fabric, as the term is here used, is the type offabric commonly used in paper making machines and is characterized by arelatively fine mesh, an ability to sustain constant movement undertension and flexure in the presence of water and to withstand frictionalabrasion.

Fourdrinier type fabric has utility for many commercial purposes butfinds its principal use in paper making machines, for which, and forother uses, the ends of a length of the screen fabric are seamed orjoined together to form an endless belt. It is important that the seambe not only strong enough to sustain the tensile strain imposed thereonin the operation of the machine, but also, in the case of papermakingmachines, that it suificiently conform to the adjacent surfaces ofthe screen as not to materially affect or objectionably mar theappearance of the surface of the paper product made thereon. If correctdrainage is lacking the paper cannot be stripped from the belt in anendless sheet.

While presently known splicing techniques are adequate for splicingall-metal foundrinier screen fabrics, such techniques are not applicableto a fourdrinier screen fabric having a warp of non-metallic yarns orfilaments.

It is the broad object of the present invention to provide seamstructures and methods of making them, applicable to fourdrinier typescreen fabric, at least the warp elements of which are non-metallic andwhich contain a synthetic organic plastic.

' Stated in another way it is an object of the invention to provide aseam geometry broadly applicable to the above stated fourdrin-ier typescreen fabrics.

A further object is to provide a scam, the transverse width of which maybe controlled, and if found desirable or necessary, restricted to awidth equal to or not substantially greater than, the transverse widthof a weft element of the fabric hein'g spliced, the thickness of theseam being similarly subject to control and restriction to a thicknessnot substantially greater than the overall thickness of the fabric.

Other and further objects and advantages of the invention will be madeapparent in the following specification and claims.

Broadly the above objectives of the invention are attained by forming arelatively narrow transversely extending body of a synthetic organicmaterial of which lapped free end portions of the warp elements,extending from the edges of the fabric to be joined, are at least-anincorporate part, adhesively and/ or cohesively bonded together into astrain resisting unit, having a per-inch tensile strength in thedirection of the warp adequately proportional to that of the per-inchstrength of the warp assembly, for the use to which the seamed fabric isto be put.

The most exacting structural limitations are perhaps imice posed in theseaming of fourdrinier screen fabric to meet the requirements of its usein the manufacture of fine quality paper, and in the followingillustrative disclosures it is assumed that the seamed fabric is to beused for that purpose, the Warp being of a synthetic organic material inthe form of a monofilament, or a staple or multifilament yarn, and theweft, by way of illustration and not limitation, being metal wire.

In the accompanying drawings which diagrammatically disclose such anillustrative embodiment of the invention:

FIG. 1 is a longitudinal sectional view, on a greatly enlarged non-exactscale, of the end portions of a length of fourdrinier type fabric,illustrating an initial step in the seaming procedure;

FIG. 2 is a view of the end portions, similar to FIG. 1 but showing theend portions prepared for the second step in the seaming procedure;

FIG. 3 is a similar view showing the third step;

FIG. 4 is a fragmentary plan view on a greatly enlarged non-exact scaleshowing the relative position of the fabric elements in correspondenceto that of FIG. 3;

FIGS. 5 to 7 are views showing succeeding steps in the seamingoperation; and

FIGS. 8 and 9 illustrate a modification in the procedure.

Referring to FIG. 1 a length of the fourdrinier fabric of the typepreviously describcd is generally indicated at l, the'non-metallicWarp-filaments being indicated at 2 and the metal shoots or weftselements at 3. As the initial step in the seaming procedure the endportions of the strip which are to be seamed together are annealed orheat treated to remove internal strains from and stabilize the warpmaterial as found necessary. The fabric ends are then trimmed to providethe needed end extension of the warp elements. For the assumed use ofthe fabric this is conveniently done by trimming along the terminalshoot wire as indicated at 4 and 5. The terminal weft or shoot wires arethen removed from each end of the strip leaving end portions 6 and '7 ofthe warp extending from the strip ends. As shown in FIG. 2 the extendingend portions are brought into the general plane of the weft and, asindicated at 8 in FIGS. 2 and 4, are flattened or otherwise shaped attheir extreme end portions by swaging or pressure, under heat if founddesirable, and cleaned to remove any processing oils, dirt, or otherforeign matter. The end portions are then brought into lapped relationas shown in FIG. 4, the extent of overlap not materially exceeding thewidth of a shoot or weft element of the fabric. Ideally and as shown theopposed warp elements are substantially aligned and the side edges ofthe flattened ends of adjacent warp elements are in substantial contact,but alignment of the opposed warp elements is not essential and thesides of the flattened end portions of the adjacent elements may lapeachother, the opposed warp ends in effect interdigitating. The end portionsof the strip are held in the position of FIGS. 3 and 4, in any suitablemanner as by bars 9 and I 10 which clamp the end portions against asupporting surface, not shown.

With the end portions so confined a suitable solvent or a plasticsolution is applied to the ends 67. The solute embedding material willdepend on the material of which the Warp filaments are formed and iseither an effective adhesive there-for oris effectively compatible andmiscible therewith to, respectively, elfect either a bonding adhesionbetween the surfaces of the lapped warp ends, or such superficialintermixing, by the solvent of the solution, as to create a unionbetween the material of the warp ends and also a union of the warp endsand the solute material. I

Nylon is one of the various synthetic organic materials commonly usedfor the warp filaments, and is below 3 referred to for one exemplarydisclosure of the seaming structure and method of the invention.

Assuming therefore that the warp filaments 2 are formed of nylon, suchas nylon 6, a nylon solvent such as phenol, preferably in the form of asolution of nylon in phenol (later more specifically described) isapplied in a single or in successive coats to both sides of the fabricat the lapped area of the filament ends by use of a dip pen, orequivalent applicator, as indicated at 12, by stippling in FIG. 6 and insection in FIG. 5. By way of example for a fourdrinier fabric of theorder of 50 to 55 mesh, the warp filaments being .011 of an inch, andthe shoot wires .0111 of an inch, in diameter, five coatings of a 5%solution of nylon in phenol has been found satisfactory. The solution ispreferably brought to a temperature of 350 F. and applied as abovedescribed. After each application the temperature of the seam area israised to a temperature suificient to drive oil the solvent, preferablyin the range of 350 F. to 375 F. After each of the first twoapplications pressure (about 5 pounds per lineal inch) may be appliedover the seam area, in order to assure that the free end portions 6 and7 are properly positioned and held in place to assure an adequate flowof the initial coating solution between and around the lapped filamentend portions 6 and 7 which define the width of the seam.

Phenol softens the nylon of the filaments sufficiently to render itsuperficially miscible with the nylon of the adjacent coatings, so thatthe coatings bond to the filaments and to each other without aperceptible or elfective interface between them. The increase of the temperature following each application of the coating solution dries thatcoating to leave it in condition to similarly miscibly accept thesucceeding coatings. Thus the warp ends 6 and 7 are integrally bondedtogether into a unitary body 12 with theresin cast from the coatings.Following the last coating operation, without drying the lattercoatings, lengths of nylon ribbon 13 and 14, each about 4 to 7 milsthick and 15 mils wide, are placed 1ongitudinally over and along theouter surfaces of the bonding body 12, as indicated in FIG. 5. Theribbons 13 and 14 are softened with hot phenol (350 F), before being putin place, and the temperature of the seam area again raised to 350 F. to375 F. Thus the resin of the end portions 6 and 7, the resin of thecoating body 12 and of the ribbons 1314 is formed into a substantiallyhomogeneous seam structure as indicated at 15 in FIG. 7. It will beunderstood that the ribbons 13 and and 14 may be applied and heated insuccessive operations or may be simultaneously integrated into the seamstructure by a single heating step following their application. Pressuremay be employed in the integration of the ribbons if found desirable.

In seaming the nylon-metal fabric of the above illustration the 5% nyloncontent of the coating solution in the above example was nylon 6/ 10,.that is the polymerization product of hexamethylenediamine containing 6carbon atoms, and sebacic acid containing carbon atoms, and the nylonribbons used were formed of 6/6 nylon, that is it is the polymerizationproduct of hexamethylenediamine containing 6 carbon atoms and adipicacid containing 6 carbon atoms. Nylon 6 or nylon 11 may be used in placeof the 6/6 and 6/10. Alcohol soluble nylon copolymers may also be used.It will be understood that the percentage of solute material in thesolution is not critical and while solutions of the order of 5%facilitate application in the manner above de scribed, percentages up tosaturation may be used as found feasible.

The above procedure and materials provide a seam which conforms closelyto the screen texture of the fabric. The cross-sectional dimensions ofthe seam and its position with respect to the adjacent fabric elementsclosely approximate those of the weft elements so that no objectionablemarking or marring of the paper made thereon results, and drainagethrough the screen is not materially impeded.

As will be apparent, where desired and where the use of the splicedscreen permits, the transverse width of the seam may be increased byincreasing the length of the free warp ends 6--7 and increasing theextent to which they are lapped, the transverse width of application ofthe embedding material and the width of the ribbon being correspondinglyincreased.

As above pointed out the embedding material may be such as makes astrong adhesive bond with the warp ends rather than a rniscible bond.For example, if the Warp comprises nylon, the embedding material may bea cyanoacrylate monomer polymerizing, preferably, at room temperature,with approximately 10% plasticizer, thickening agent and stabilizer; thematerial available under the trade name Eastman 910 being an example.Such material may be applied in successive coats in the manner abovedescribed, the coats being allowed to cure under pressure as foundnecessary (about 5 pounds per lineal inch). The monomer may bealuminum-filled (up to 10% by weight) with some increase in the strengthof the bond, but aluminum powder accelerates the cure of the resin.Strips l3 and 14 of nylon may be pressed into bonding adherence to thefinal coating of the embedding adhesive. Any of the various commerciallyavailable adhesives which make a strong bond with nylon,

such as the phenolic butyral adhesives, exemplified by rial, it onlybeing necessary to use solvents, and bonding agents which areappropriate for the resin of which the Warp elements are formed. For afurther example, assuming the warp elements are formed of polyesterresin such as polyethylene terephthalate, the warp ends, having beensuitably shaped or flattened as in FIG. 2 and cleaned, may be lapped tothe desired extent. In this example the bonding 12 may comprise one ormore coatings of asuitable solvent such as m-chloro-aniline or phenol,preferably with about 5% polyethylene terephthalate in the solvent,successively applied at a temperature of 350- 420" F. to opposite sidesof the lapped warp ends with the latter at approximately the sametemperature and with pressure applied at that temperature for aboutthree minutes, and the coatings cooled to room temperature underpressure. Ribbons 13 of polyethylene terephthalate V film may then beincorporated at opposite sides of the coating body 12. Such ribbons maybe coated with a polyester adhesive. For example a 3 mil polyethyleneterephthalate ribbon with 2 mil coating of 46971 Mylar adhesive by DuPont may be employed.

In seaming heavier fabrics than that of the example above given or wherefor manufacturing conditions or other reasons ditliculty is encounteredin maintaining the width of the seam within the desired width,additional steps shown in FIGS. 8 and '9 may be employed. Prior to orafter trimming the fabric as described but before removal of the endshoot, the mesh'of the fabric for a short distance back of the fabricends may be filled with 'ashown in FIGS. 3 and 4. The forming of theseamstructure may then be proceeded with as above described,

or the space between the barriers 16 may be bridged with a mold plates,not shown, and the cavity formed by the barriers 15 and the platesfilled with the bonding composition by injection or otherwise. In anyevent after the seaming structure has been formed the barriers 16 aredissolved away by a suitable solvent or removed by manual stripping, airblasting, or other suitable procedure.

What is claimed is:

1. In a fourdrinier screen fabric having a non-metallic warp containingsynthetic organic material, a seam comprisin lapped end portions of theWarp elements embedded in a body of synthetic organic material, saidbody extending transversely of the fabric between and parallel to weftelements of the fabric and bonding the embedded warp ends to each otherand to said body, said body including a preformed strip of the warpmaterial extending longitudinally thereof and incorporated therein.

2. In a fourdrinier screen fabric having a non-metallic warp containingsynthetic organic material, a seam comprising flattened end portions ofthe warp positioned in lapping relation substantially in the plane ofthe weft and embedded in a body of synthetic organic material extendingtransversely of the fabric between, spaced from and parallel to theadjacent weft elements of the fabric and bonding the embedded warp endsto each other and to said body.

3. A seam as in claim 2, the warp elements being nylon and said bodycomprising nylon.

4. A seam as in claim 2, the Warp elements being nylon and said bodycomprising one or more integrated coatings of nylon and preformed stripsof nylon superposed on opposite sides of said body.

5. A seam as in claim 2, the warp elements being nylon and the bodycomprising one or more superposed coatings of polycyanoacrylate.

6. A seam as in claim 2, the warp elements being nylon and the bodycomprising one or more superposed coatings of polycyanoacrylate andpreformed strips of nylon superposed on opposite sides of said body.

7. A seam as in claim 2 the warp elements and said body comprising apolyester resin.

8. A seam as in claim 2., the Warp elements being polyethyleneterephathale and the body comprising superposed coatings of up to 5%polyethylene terephthalate in mchloro-aniline.

9. A seam as in claim 2, the warp elements being polyethyleneterephthalate and the body comprising superposed coatings of up to 5%polyethylene terephthalate in m-chloro-aniline, and preformed strips ofpolyethylene terephthalate superposed on opposite sides of said body.

10. The method of seaming together warp edges of a fourdrinier screenfabric having a warp containing synthetic organic material whichcomprises, clearing the said edges of weft elements as needed to provideextending Warp end portions, at each edge, cleaning the extending warpend portions, bringing the extending warp end portions at said edgesinto lapped relation and applying a synthetic organic material to saidlapped end portions to form an embedding body around the lapped endportions to bend said portions together and to said body.

11. The method of claim '10 in which said embedding body is formed bythe application of successive coatings of a solution of embeddingmaterial to the lapped warp end portions at opposite sides of thefabric.

12. The method of seaming together warp edges of a fourdrinier screenfabric having a warp containing synthetic organic material whichcomprises clearing the said edges of weft elements as needed to provideextending warp end portions, at each edge, flattening the ends of saidportions, cleaning the ends, bringing the opposed extending Warp endportions into substantial alignment at said edges and into lappedrelation and applying a synthetic organic material to said lapped endportions to form an embedding body around the lapped end portions tobond said portions together and to said body.

13. The m thod of seaming together warp edges of a fourdrinier screenfabric having a warp containing synthetic organic material whichcomprises, clearing the said edges of weft elements as needed to provideextending Warp end portions, at each edge, cleaning the ends, bringingthe extending Warp end portions at said edges into lapped relation,applying successive coatings of a synthetic organic material to saidlapped end portions at opposite sides of the fabric, and applyingpreformed solvent-softened strips of the warp material over saidcoatings at opposite sides of the fabric.

14. The method of seaming together warp edges of a fourdrinier screenfabric, having a warp of nylon which comprises clearing the said edgesof weft elements as needed to provide extending warp end portions ateach edge, cleaning the ends, bringing the extending warp end portionsat said edges into lapped relation, and applying to said lapped endportions at both sides of the fabric, successive coatings of a viscoussolution of nylon, raising the temperature of the seam area followingeach coating operation to substantially drive off the solvent, applyingslight pressure to at least the initial coating prior to the applicationof the successive coatings.

15. The method of seaming warp edges of a fourdrinier screen fabric,having a warp of nylon, which comprises clearing the said edges of weftelements as needed to provide extending warp end portions at each edge,cleaning the ends, positioning the extending warp end portions inlapping relation substantially in the plane of the weft members,applying to the so-positioned extending warp end portions, atboth sidesof the fabric, successive coatings of a 5% solution of nylon in phenolat a temperature of substantially 350 F., raising the temperature of theseam area, following each coating operation, to a temperature in therange 350 F. to 375 F. to drive oft" the solvent, applying a pressure ofapproximately 5 pounds per lineal inch to at least the initial coatingprior to the application of the successive coatings, and applying astrip, 4 to 7 mils thick and approximately 15 mils wide, of nylonsoftened with phenol at a temperature of 350 F., longitudinally over thecoatings at each side of the fabric, and again raising the temperatureof the seam area to a temperature in the range 350 F. to 375 F.

16. The method of seaming warp edges of a fourdrinier screen Wabric,having a warp of nylon, which comprises clearing the said edges of weftelements as needed to provide extending warp end portions at each edge,cleaning the ends, positioning the extending warp end portions inlapping relation substantially in the plane of the weft members,applying to the so-positioned extending warp end portions, at both sidesof the fabric, successive coatings of a cyanoacrylate monomer, andcuring the successive coats to form an embedding body around the lappedportions'of the extending Warp ends.

17. The method of claim 16 in which the eyanoacrylate monomer is filled,up to 10% by weight with finely divided aluminum.

18. The method of seaming warp edges of a fourdrinier screen fabric,having a warp of nylon, which comprises clearing the said edges of weftelements as needed to provide extending warp end portions at each edge,cleaning the ends, positioning the extending warp end portions inlapping relation substantially in the plane of the Weft members,applying to the so-positioned extending Warp end portions, at both sidesof the fabric, successive coatings of a cyanoacrylate monomerpolymerizing at room temperature, allowing the successive coats to cureunder contact pressure, to form an embedding body around the lappedportions of the extending Warp ends and pressing a strip of nylon intobonding adherence with the embedding body.

19. The method of seaming warp edges of a fourdrinier screen fabric,having a warp of polyethylene terephthalate, which comprises clearingthe said edges of weft elements as needed to provide extending warp endportions at each edge, cleaning said portions, positioning the extendingwarp end portions in lapping relation substantially in the plane of theweft members, heating the so-positioned extending warp end portions to'a temperature of approximately 350 F. to 420 F., applying successivecoats of approximately polyethylene terephthalate in m-chloro-anilineheated to a temperature of approximately 350 F. to 420 F. to theso-positioned extending warp :end portions.

20. The method of seaming warp edges of a fourdrinier screen fabric,having a warp of polyethylene terephthalate, which comprises heattreating the fabric at, and for a substantial distance rearwardly from,the edges to be joined to stabilize the material of the warp, clearingsaid edges of weft elements as needed to provide warp end portions ateach edge, flattening the ends of said portions, cleaning the said endportions, bringing the flattened end portions into lapped relation,heating the so-positioned warp end portions to a temperature ofapproximately 250 F., applying successive coats of hot phenol thereto,raising the temperature of said warp end portions to approximately 420F. under pressure, permitting evaporation of the phenol, applying hotphenol to ribbons of polyethylene terephthalate and to the now cool warpend portions,-at each side of the fabric, and applying the said ribbons,successively one to each side of the fabric, over the warp end portions,under pressure and at a temperature approximating 420 F.

21. The method of seaming together warp edges of a fourdrinier screenfabric having a 'warp containing synthetic organic material whichcomprises trimming the edges along a weft element, filling the mesh ofthe fabric rearwardly of said weft element with a barrier material,

rial as needed to provide extending warp end portions extending from theremaining barrier material, bringing the so-extending wrap end portionsinto lapped relation, forming an embedding body of a synthetic organicmaterial around the said lapped end portions between the adjacent edgesof the barrier material to bond said Warp end portions together andthereafter cleaning the fabric of said barrier material.

22. The method of seaming together warp edges of a fonrdrinier screenfabric having a warp containing synthe'tic organic material whichcomprises trimming the edges along a weft element, filling the mesh ofthe fabric rearwardly of said weft element with a barrier material,clearing the said edges of Weft elements and barrier material as neededto provide extending warp end portions extending from the remainingbarrier material, bringing the soextending warp end portions into lappedrelation, filling the space between the adjacent edges of the barriermaterial with a material bonding the said warp end portions together andthereafter clearing the fabric of said barrier material.

References Cited in the tile of this patent UNITED STATES PATENTS2,049,752 Steinhart Aug. 4, 1936 2,116,812 Webb May 10, 1938 2,117,222Sinclair May 10, 1938 2,391,731 Miller et a1 Dec. 25, 1945 2,435,467Spencer Feb. 3, 1948 2,903,021 Holden et a1 Sept. 8, 1959

1. IN A FOURIDRINIER SCREEN FABRIC HAVING A NON-METALLIC WARP CONTAININGSYNTHETIC ORGANIC MATERIAL, A SEAM COMPRISING LAPPED END PORTIONS OF THEWARP ELEMENTS EMBEDDED IN A BODY OF SYNTHETIC ORGANIC MATERIAL, SAIDBODY EXTENDING TRANSVERSELY OF THE FABRIC BETWEEN AND PARALLEL TO WEFTELEMENTS OF THE FABRIC AND BONDING THE EMBEDDED WARP ENDS TO EACH OTHERAND TO SAID BODY, SAID BODY INCLUDING A PREFORMED STRIP OF THE WARPMATERIAL EXTENDING LONGITUDINALLY THEREOF AND INCORPORATED THEREIN.